Process for producing lubricating oil additives



Dec. 16, 1958 J. T. GRAGSON PROCESS FOR PRODUCING LUBRICATING OILADDITIVES Filed Dec. 3, 1954 INVENTOR. J. T. GRAGSON BY MM 3% MMV PROCESS FOR PRDUCL\IG LUBRCATING @EL ADD'HVES .lames T. Gragson, Bartlesville, kla., assigner to Phillips Petroleum Company, a corporation of Delaware Application December 3, 1954, Serial No. 472,896

7 Claims.. (Cl. 260-452) This invention relates to lubricating compositions. In one of its more specific aspects this invention relates to lubricating oil additives. In another of its more specific aspects it relates to a lubricating oil additive composition having both detergent and corrosion inhibiting properties. In still another of its more specific aspects it relates to ya method for the production of a detergent and corrosion inhibiting lubricating oil additive composition.

The lubricating oils employed in internal combustion engines, such as automobile engines, diesel engines and gas-fueled stationary engines, require the use of additive agents to render them serviceable under conditions of high temperature operation and continuous operation on the one hand, and under sludge forming conditions of stop and start operation in cold weather, on the other hand. It is common practice to add modifying: agents to lubricating oils to control oxidation of the oil and to reduce corrosion of metal parts in contact with the oil. Compounds which have the desired effect of reducing corrosion caused by the lubricating oil usually adversely affect the sludge and piston varnish forming characteristics of the oil.

It has been found that controlled oxidation of certain selected fractions of lubricating oil produces a completely ashless material having excellent detergent properties when added to a lubricating oil. This detergent material substantially reduces the piston varnish formation tendencies of a lubricating oil with no adverse effects upon the results obtained by the other additive agents. The process for producing these detergent materials is described and claimed in copending application SerialV No. 304.659, led August 15, 1952, by W. B. Whitneyynow abandoned.

One method for the controlled oxidation of lubricating oil fractions is that practiced on topped crude oils obtained from any source, for example, Pennsylvania, Mid Continent, California, East Texas, Gulf Coast, Venezuela, Borneo, and Arabian crude oils. In this method for the preparation of the detergent material, a crude oil is topped, i. e., distilled to remove therefrom more Volatile lower molecular weight hydrocarbons such as gasoline and light gas oil, and then vacuum reduced to remove heavy gas oil and light lubricating oil of the SAE-10 and 20 viscosity grade. The vacuum reduced crude is then propane fractionated to remove additional heavier fractions of lubricating quality hydrocarbons.

Following the propane fractionation step, the overhead oil fraction is solvent extracted with a selective solvent which will separate the paraflinic hydrocarbons from the more aromatic type hydrocarbons. This solvent extraction step for the removal of the more highly aro-matic compounds can be carried out in accordance with the well known concurrent or countercurrent solvent extraction techniques which are well known in the art.

The resulting solvent extracted material, before or after the removal of the more aromatic hydrocarbons, is preferably dewaxed. The dewaxing can be carried out by any conventional method, e. g., by solvent dewaxing ice using propane or other known solvents and solvent mixturesV such as methylethylketone or methylisobutylketone with benzene at a suitable temperature.

Other suitable methods of preparing a satisfactory feedstock are described in more detail in the above referred to copending application.

A preferred feed material for the oxidation reaction is a substantially saturated hydrocarbon fraction having at least 40 carbon atoms per molecule, preferably between 40 and 80 carbon atoms per molecule, a refractive index nD20 of between 1.440 and 1.520, an average molecular weight between 550 and 1300, a viscosity of between 50 and 1400 SUS at 210 F., and a viscosity index, when determinable, of between 50 and 125.

The oxidizing reaction is accomplished by contacting a selected hydrocarbon fraction, as hereinbefore described, under suitable conditions of temperature and pressure with an oxidizing agent such as free oxygen, sulfur trioxide, nitrogen dioxide, nitrogen trioxide, nitro gen pentoxide, acidied chromium oxide and chromates, permanganates, peroxides, such as hydrogen peroxide, and sodium peroxide, nitric acid, and ozone. Any oxygencontaining material capable of releasing free oxygen under the oxidizing conditions can be used. Air is a preferred oxidizing agent from the standpoint of economy.

Generally the oxidation reaction is carried out at a temperature in the range of from 40 F. to 800 F. When air is used as the oxidizing agent, temperatures in the range of F. to 800 F., preferably 390 F. to 575 F. are generally used. When nitric acid is used as the oxidation agent, temperatures ranging from room temperature up to 200 F., preferably 140 F. to 170 F. are ordinarily used.

When a gaseous oxidizing agent is used, the partial pressure of the oxidizing agent operates to reduce the rate of oxidation, therefore, the oxidation reaction can be considered to proceed at a faster rate by increasing the pressure in the reaction zone. The oxidation reaction can be carried out at sub-atmospheric, atmospheric or super-atmospheric pressure. The reaction is preferably carried out at a pressure of between about l0 to 100 pounds per square inch absolute depending upon the composition of the oxidizing gas.

Catalysts can be used to promote the oxidation reaction and these catalysts include the various well known oxidation catalysts such as the oil-soluble salts and compounds containing such metals as copper, iron, cobalt, lead, zinc, cadmium, silver, manganese, chromium, vanadium, and the like, and an atomic number between 51 and 113, inclusive. Especially useful and outstanding as a catalyst are those compounds obtained by reacting a compound containing both phosphorus and sulfur, such as P285, with a terpene, either monocyclic or dicyclic or amixture thereof, such as pinene as disclosed in copending application Serial No. 264,839, led January 3, 1952, now U. S. Patent No. 2,758,069, by W. B. Whitney. A particularly effective catalyst of this type is Widely used as a corrosion inhibitor for petroleum lubricating oils and is a PgSyterpene reaction product.

The controlled oxidation of a lubricating'oil fraction modifies the oil in at least four physical characteristics. These characteristics are as follows: (l) an increase in the carbon to hydrogen weight ratio, (2) an increase in oxygen content, (3) an increase in molecular weight, (4) and a decrease in solubility in propane under propane fractionating conditions.

The reaction can be followed and controlled by measuring the water formed, by measuring the increase in viscosity, and by measuring the detergent activity by the carbon dispersion spot test because it has been found that all of the values increase during the course of the reaction. The carbon dispersion spot test is described in application Serial No. 304,659 referred to herein'befo're.

The oxidation reaction is usually conducted until from to 50 percent, preferably 425 to.40 percent, of the hydrocarbon has been oxidied When 'an 'oil having la viscosity in the range o'f 100 to 240 SUS at 210 F. 1s utilized in the oxidation reaction, it has been found that the yield of detergent material can be controlled in the abo've range of 25 to 40 percent by stopping the reaction when the viscosity of the oil has been raised lto the range from 600 to 800 SUS at 210 F.

A parafnic lubricating oil without additives is usually corrosive. For example, in a conventional test anuninhibited base oil was found to have a bearing loss of S71 milligrams and a piston varnish rating of 7.4. :The addition of a commercially available P2S5-terpene conv densation product corrosion inhibitorreduced the bearing weight loss to a` satisfactory low level of 12 to `15 milligrams but the piston varnish rating dropped to 3.0. When both the corrosion inhibitor and a detergent, prepared according to the method of this invention, were added to the base oil, the resulting modified oil was satisfactory "with respect to both bearing weight loss and piston varnish rating. Thus it has been shown that corrosion inhibitors are required in order `to prevent undue wear on `the working parts of an internal combustion engine and that a detergent Vis necessarysin addition to the corrosion inhibitor to prevent undue formation of piston varnish.

Each-of the following objects will be attained by at least one of the aspects of the invention.

It is an object of this invention to provide improved lubricating oil compositions.

It is another object to provide an additive for lubricating oils having both detergent and corrosion inhibiting properties.

It is another object to provide a method for producing an improved lubricating oil additive.

It is still another object to provide a method for producing a lubricating oil additive having both detergent and corrosion inhibiting properties.

Other and further objects and advantages will be apparent to one skilled in the art upon study of the disclosure of this invention and the attached drawing wherein:

The single figure is a fiow sheet representing a preferred form of the process of this invention.

I have discovered new lubricating oil additive agents having both detergent and anti-oxidant properties which are prepared by the following sequence of steps: (l) oxidation of refined parafiinic lubricating oil of SAE- or higher viscosity with air, nitric acid, or other oxidizing agent under conditions hereinbefore set forth,` (2) treating this oxidized oil fraction with phosphorus pentasulfide (P255), (3) and neutralizing the treated oil With barium hydroxide or other alkaline earth oxides. This additive provides superior detergent and anti-oxidant properties in a lubricating oil.

The oxidized lubricating oil fraction prepared according to the conditions hereinbefore set forth and described in more detail Tin copending application Serial No. 304,659, `filed August 15, 1952, by W. B. Whitney, now abandoned, is treated with P285 in the powdered form in an amount of 0.1 to20 Weight percent and preferablyS to l5 weight'percent of P285 of the total oxidized lubricating oil fraction. The broad range of reaction temperature can be from 250 `to 450 F. with the preferred reaction temperature being inthe range of 300 to 400 F. The treated oxidized lubricating 'oil fraction is heated, withgentle agitation, until all of the hydrogen sulfide, liberated by the reaction, is removed from the material. This heating-step canbe continued for aperiod of time inthe range `5`minutesito 5 lioursb'ut usually and preferably is continued for a time in the range of 1 hour to 4hours. c

The product is then treated with barium hydroxide or other alkaline earth oxides or hydroxides.

Representative compounds include calcium oxide, calcium hydroxide, calcium carbonate, barium oxide, barium hydroxide, strontium oxide, and strontium carbonate. The treatment with the alkaline earth compound is preferably done by dissolving the oxidized material in a suitable solvent, such as benzene or toluene, and adding the alkaline earth compound thereto. Other solvents which can be used include light oils such as SAE-l0 oil and other normally liquid light hydrocarbons, such as pentane or hexane. Frequently it is advantageous to add Va small amount of a non-solvent, such as isopropyl alcohol, in order to obtain better contacting. This is especially true when an aqueous solution of the alkaline earth material is used. The alkaline earth material is added as an aqueous solution, an aqueous slurry, or as a finely powdered material, in a concentration of 0.1 to 20 weight percent and preferably 0.5 to l0 weight percent of the total charge. Following the addition, the mixture is preferably stirred for a sufiicient length of time to ensure adequate reaction. Temperatures for the reaction can range from room temperature to 550 F. although the preferred range of temperature is from 175 to 300 F. If an aqueous solution or an aqueous slurry -of the alkaline earth compound is used, a reaction temperature 'sufficiently high so as to expel the water can be used. Benzene is a preferred solvent because a benzene and water azeotrope is formed which boils off at a temperature below the boiling point of water. A reaction time of 5 minutes Vto 5 hours will usually be sufficient to ac'complishthe required reaction. The resulting solution is filtered to remove excess alkaline earth material and any other insoluble material. The resulting product, after filtration, is an oil concentrate containing the additive which can beadded to any desired lubricating oil base stock directly, or the additive can be separated from the oil concentrate if desired.

In compounding the improved oil compositions provided by this invention, the additive is added to the desired oil base in `an amount sufficient to obtain the desired degree of -improvement in service characteristics of theoil. This amount will accordingly depend on the characteristics of the oil `itself as well as to the conditions to which the oil is subjected in use. Ordinarily the additiveA is employed in an amount between 0.1 and l5 percent by weight of the entire composition but can be as 'high as 25 percent in cases of extreme service conditions. Usually an vamount in the range 0.3 to 10 percent by weight is sufficient. The base oil can be any oil of suitable grade and viscosity obtained by any of the modern refining methods. The detergent and anti-oxidant additive of this invention Afunctions independently of other types of additives without materially altering the physical characteristics of the oil and accordingly the base can contain other additive agents, such as viscosity index improvement agents, pour point depressants, and the like.

Y In the drawing which accompanies and forms a part of this disclosure, there is illustrated apparatus for preparing the additives of this invention. This apparatus comprises an elongated vessel 10 having an oil inlet 11 and oxidizing agent inlet 12, a gas vent 13, and an oxidized oil efiiuent conduit 14. Oxidizing agent inlet 12 terminates 1n a gas distributing means 15 for breaking up the oxidizing agent intofine bubbles. If a liquid oxidizing agent, having a density greater than that of the oil, such as nitric acid is utilized, the oil inlet 11 and the oxidizing agent inlet `12 are reversed. A distributing means is preferably utilized on eachinlet. In this manner changing Vfrom one type'of oxidizing agent to another can be accomplished .by merely reversing the introduction of oil andfoxidizing agent. A coil 16, which can be a steam asefgsae heated coil or other heating means, is positioned in vessel for maintaining the reactants at the required temperature. A plurality of heating elements can be employed if desired. The oxidized oil ethuent from vessel 10 flows into a wash vessel 17 where it is contacted with water admitted through line 18. The oil passes out of vessel 17 through line 19 and into vessel 21 where the oil is contacted with a drying material such as alcohol which is admitted by way of conduit 22. The oil passes out of the vessel 21 by way of conduit 23 and enters vessel 24 containing a stirrer 25 actuated by a source of power not shown. P285 is added to vessel 24 by means of conduit 26 and the treated oil leaves vessel 24 by way of conduit 27' and passes to vessel 28 containing stirrer 29 actuated by a source of power not shown. An alkaline earth oxide or hydroxide is admitted to vessel 28 by means of conduit 30. The treated material leaves vessel 28 by way of conduit 31 and passes to ilter 32. The product leaves lter 32 by way of conduit 33 and can be used as produced or can be separated from the oil concentrate by solvent extraction in conventional solvent extraction equipment not shown.

In the operation of this apparatus, the oil is introduced to the upper portion of vessel 10 so as to flow countercurrently to an oxidizing gas introduced in the lower portion of the vessel 10. The points of introduction of oil and oxidizing agent are reversed if a liquid oxidizing agent, having a density greater than that of the oil, is used. The oxidized oil, after suitable reaction time, passes from the lower portion of vessel 10 to a wash vessel 17 wherein acidic materials are removed and the oil eluent from wash tank 17 is then passed through a vessel and contacted countercurrently with a material capable of removing entrained water such as alcohol. The washing step is necessary when an oxidizing agent such as nitric acid is employed but can be omitted when a dry oxidizing gas, such as dried air, is employed. The oxidized oil is passed to treating tank 24 wherein it is contacted with P285 while being gently agitated by the stirrer 25. Heat can be added to vessel 24 if additional heat is required. The P285 treated oil is then passed to treater 28 wherein it is contacted with an alkaline earth oxide or hydroxide and gently agitated by means of stirrer 29. The alkaline earth treated material is then passed through filter 32 which can be a conventional sand lter or other known iilter means where solid particles are removed therefrom. The product emerging from the filter 32 can be used as produced or alternatively the additive can be removed from the concentrate by solvent extraction, by known means using as a solvent propane, liquid sulfur dioxide or other suitable solvent.

The following examples illustrate the invention but are not to be considered to limit the invention.

EXAMPLE I A solvent reiined and dewaxed lubricating oil derived from Mid-Continent petroleum, having a viscosity of 4278 SUS at 100 F., a viscosity of 203 SUS at 210 F. and a viscosity index of 93, and designated as 250 oil was reacted for 3 hours at 160 F. and at atmospheric pressure with an equal volume of nitric acid. The nitric acid utilized was commercial nitric acid containing` approximately 65 weight percent HNO3 and was diluted with an equal volume of water. The treated oil was washed with water and the emulsion broken by the addition of isopropyl alcohol. The oily layer was separated, freed of solvent, and treated at a temperature of 32C-350 F. with ten percent P285. The oil was agitated at this temperature for 31/2 hours and then allowed to cool. The material was diluted with benzene and decanted from any unreacted P2S5 and finally treated with a saturated aqueous solution of Ba(OH)2-8I-I2O at the boiling point of the mixture. Neutralization was considered to be complete when a small sample, freed of Water and excess barium hydroxide, in a blend of lubricating oil shwed 6 no discoloration of a copper strip after warming 30 minutes in a water bath. The product, when neutralized, was freed of water (as a benzene-water azeotrope) and the material centrifuged and the solvent evaporated.

A base oil and a sample of the base oil containing the additive prepared as above were submitted to the Lauson engine test. The test consisted in placing 920 grams of the oil composition in the crankcase of a single cylinder Lauson gasoline engine. The engine was operated under a 1.2 H. P. load at 1600i20 R. P. M. maintaining a cooling jacket temperature of 300 F., an oil temperature of 225 F. and an air-to-fuel ratio of 13.5 :1. At the end of 60 hours` of operation under these conditions, the engine was stopped, disassembled, and the piston, crankcase, and bearings were examined. The piston varnish was rated on a scale of 1 to 10 in which l0 represented a clean or perfect condition and l represented the dirtiest condition.

The above tests were conducted using a baseoil having ther characteristics shown in Table I.

Table I Gravity API v 30.3 Viscosity at 210 F 61.8 ViSCOSty index 98 Neutralization number 0.01

The results of the Lauson engine test are shown in Table II.

An additive material was made according to the process described in Example I except that the treatment with barium hydroxide was omitted. The additive as prepared contained 0.65 weight percent sulfur. The results of the Lauson engine test are shown in Table III.

Table lll Wt. Per- Piston Bearing Sample cent of Varnish Wt. Loss Additive in Mg.

Base Oil 0 6. 0 182 Base Oil plus Additive 1. 75 4. 7 696 The results of Example I show that the additive material of this invention is an excellent lubricating oil additive having both detergent and corrosion inhibiting properties. The results of Example II show that the treatment with an alkaline earth oxide or hydroxide is necessary in producing the additives of thisv invention.

EXAMPLE III A detergent composition was prepared from a 250 oil as described in Example I according to the procedure set forth in Example I. A sample of this detergent cornposition was analyzed for ash content and the ash content was found to be 13.8 weight percent.

Variations and modifications are possible within the scope of the disclosure of this invention, the essence of which is the production of a superior lubricating oil additive composition having both detergent and corrosion inhibiting properties by the treatment of an oxidized lubricating oil fraction with P285 and an alkaline earth oxide or hydroxide.

That which is claimed is:

l. A process for producing a lubricating oil additive having both detergent and anti-oxidant properties which comprises subjecting a relined paraiiinic lubricating Oil having a viscosity of at least SAE-2O to oxidation in the presence of nitric acid having a concentration of 25 to 40 weight percent HNO3 at a temperature in the range of 140 to 170 F. for a period of time in the range 4 to 10 hours, contacting the resulting oxidized oil with a sufcient amount of water so as to remove nitric acid; contacting the washed oil with a suicient amount of alcohol so as to remove remaining water; contacting the washed and dried oil with from 5 to 15 weight percent of phosphorus pentasulfide for a period of time in the range l hour to 4 hours at a temperature in the range 300 to 400 F.; diluting a resulting product with an equal volume of benzene; contacting a resulting product with a saturated aqueous solution of an alkaline earth compound selected frorn the group consisting of alkaline earth hydroxides, oxides, and carbonates in an amount of 0.5 to 10 Weight percent of the total charge; agitating the mixture for a period of time in the range of 5 minutes to 5 hours at a temperature in the range of 175 to 300 F.; filtering the resulting product so as to remove solid particles therefrom; and recovering the filtrate as the lubricating oil additive.

`2. The process of claim 1 wherein the alkaline earth compound is calcium hydroxide.

3. The process of claim 1 wherein the alkaline earth compound is barium hydroxide.

4. The process of claim 1 wherein the alkaline earth compound is strontium carbonate.

5. A process for producing a lubricating oil additive having both detergent and antioxidant properties which comprises subjecting a refined parainic lubricating oil having a viscosity of at least SAE-2O to oxidation in the presence of nitric acid until from 15 to 50 percent of the oil has been oxidized; removing remaining nitric acid; adding at least a stoichiometric amount of phosphorus pentasulde to the oxidized oil and heating the mixture until evolution of hydrogen sulde has ceased; neutralizing th'e resulting reaction product with an alkaline earth compound selected from the group consisting of alkaline earth hydroxides, oxides, and carbonates; and recovering the neutralized product as the lubricating oil additive.

6. The process of claim 5 wherein the alkaline earth compound is calcium hydroxide.

7. The process of claim 5 wherein the alkaline earth compound is barium hydroxide.

References Cited in the le of this patent UNITED STATES PATENTS 2,337,336 McCluer et al Dec, 2l, 1943 2,410,642 Farkas et al Nov. 5, 1946 2,419,325 Musselman Apr. 22, 1947 2,647,889 Watson et al Aug. 4, 1953 2,682,553 Kirk et al. June 29, 1954 2,691,002 Bartleson et al. Oct. 5, 1954 2,698,296 Musselman et al Dec. 28, 1954 

1. A PROCESS FOR PRODUCING LUBRICATING OIL ADDITIVE HAVING BOTH DETERGENT AND ANTI-OXIDANT PROPERTIES WHICH COMPRISES SUBJECTING A REFINED PARAFFINIC LUBRICATING OIL HAVING A VISCOSITY OF AT LEAST SAE-20 TO OXIDATION IN THE PRESENCE OF NITRIC ACID HAVING A CONCENTRATION OF 25 TO 40 WEIGHT PERCENT HNO3 AT A TEMPERATURE IN THE RANGE OF 140 TO 170*F. FOR A PERIOD OF TIME IN THE RANGE 4 TO 10 HOURS, CONTACTING THE RESULTING OXIDIZED OIL WITH A SUFFICIENT AMOUNT OF WATER SO AS TO REMOVE NITRIC ACID; CONTACTING THE WASHED OIL WITH A SUFFICIENT AMOUNT OF ALCOHOL SO AS TO REMOVE REMAINING WATER; CONTACTING THE WASHED AND DRIED OIL WITH FROM 5 TO 15 WEIGHT PERCENT OF PHOSPHORUS PENTASULFIDE FOR A PERIOD OF TIME IN THE RANGE 1 HOUR TO 4 HOURS AT A TEMPERATURE IN THE RANGE 300 TO 400*F.; DILUTING A RESULTING PRODUCT WITH AN EQUAL VOLUME OF BENZENE; CONTACTING A RESULTING PRODUCT WITH 